The present invention relates generally to a thermal dissipation assembly for use with electronic components and more particular to a thermal dissipation assembly with improved electrical short resistance.
Electronic assemblies are designed in a wide variety of configurations for a wide variety of individual applications. It is common for these electronic assembles, however, to include electronic components that generate heat during operation. Although this generated heat may be acceptable in certain assemblies and applications, in others this generated heat poses a danger to the electronic assembly. Generated heat my result in damage to the electronic component, surrounding components, or the electronic assembly as a whole. In addition, many electronics components fail to operate properly if their temperatures are not kept within a predetermined range. It is therefore, usually highly desirable to dissipate heat generated within the electronics assembly.
One standard approach to the dissipation of heat generated within the electronic assembly is through the use of heat sink components. Heat sink components are well known in the prior art and may take on a variety of forms, including cases, heat rail brackets, and a host of other embodiments. The heat sink component allows heat generated by electronic components to pass into the heat sink and thereby allow the heat generating electronic components to remain at a safe temperature. The heat sink component must remain in sufficient thermal contact with the heat generating electronic component in order to properly dissipate the electronic component""s heat. Although the heat sink component must retain sufficient thermal contact, in many applications it must also retain electrical separation from the electronic components. If electrical separation is not maintained, electrical shorts and failure of the electronics assembly may occur. The existence of electrical shorts is known to result in decreased customer satisfaction, increased scrap costs, poor product performance, and increase warranty costs.
One successful method of providing thermal communication while retaining electrical separation has been through the use of thermally conductive adhesives. By filling the gap between a heat generating electronics component and the heat sink with thermally conductive adhesive, heat is allowed to pass from the electronics component into the heat sink. In addition, thermally conductive adhesives are commonly not electrically conductive and therefore can be used to provide the electrical separation between the heat generating electronics component and the heat sink. Although thermally conductive adhesives may be non-conductive and therefore provide electrical separation between the electronics component and the heat sink, often the thermally conductive adhesives do not provide the physical barrier necessary to separate the electronics component from the heat components until the thermally conductive adhesive is cured. As an example, when the substrate of an electronics assembly is mounted to the heat sink, the heat generating electronics component may be pressed towards the heat sink due to the clamping forces created between the substrate and the heat sink. This can still cause the electronics component to penetrate the thermally conductive adhesive and come in contact with the heat sink components during assembly. As has been discussed, contact between the electronics component and the heat sink can result in electrical shorts and other undesirable results. A solution to prevent such penetration would be desirable.
One solution, found in the prior art, to providing the required physical separation while using thermally conductive adhesives has been to introduce glass beads into the thermally conductive adhesive. The glass beads, commonly distributed randomly in the adhesive, are used as a physical separator between the electronics component and the heat sink component in order to reduce penetration of the electronics component through the adhesive. Although glass beads have been developed to reduce in incidents of electrical shorts, ironically they may actually cause such faults in certain situations. Often as portions of electronics assembly are mounted to the heat sink (or experience other assembly processes) the gap between the electronics component and the heat sink experience clamping forces. These clamping forces can force the glass beads during manufacturing to penetrate the soft heat conducting surfaces of the electronics component or heat sink. When these glass beads penetrate, they can push out the metal around them, and thereby cause an electrical short between the electronics component and the heat sink surface or even an electrical short within the electronics component itself. This may not only cause the assembly to malfunction, but it may also result in precisely the same undesirable result that the glass beads were originally designed to avoid. Although this scenario may be avoided by precise control of the clamping forces or improved control of spacing tolerances, this is often not practical due to the variation in thickness of electronic components from various manufacturers. The variation in thickness of various electronic components can require adjustments in assembly tolerances and forces that are impractical or costly to implement. Implementing such precise control over the clamping forces may result in undesirable increases in complexity, cost, and assembly time.
It would, therefore, be highly desirable to have a thermal dissipation assembly that provided the benefits of thermally conductive adhesives, that provided adequate physical separation between the electronics component and the heat sink components, and that had a reduced sensitivity to clamping forces during assembly.
It is, therefore, an object of the present invention to provide a thermal dissipation assembly for use with an electronics assembly that provides thermal dissipation between an electronic component and a heat sink while providing adequate electrical and physical separation between the two components. It is a further object of the present invention to provide a thermal dissipation assembly with reduced sensitivity to assembly clamping forces.
In accordance with the objects of the present invention, an electronics assembly is provided including a heat generating component and a heat sink positioned in relation with one another to form a gap. A plurality of pre-cured thermal conductive material elements are positioned within the gap to create a physical barrier between the heat generating component and the heat sink. A post-cured thermal conductive material fills in the gap allowing the thermal energy from the heat generating component to be transferred to the heat sink.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.